Dietary isoflavones affect sex hormone-binding globulin levels in postmenopausal women

J Clin Endocrinol Metab. 2000 Aug;85(8):2797-800. doi: 10.1210/jcem.85.8.6750.


The studies presented in this report were designed to further investigate the causal association between phytoestrogen action and increase in sex hormone-binding globulin (SHBG) levels. Phytoestrogens include isoflavones that bind to estrogen receptors and therefore exert estrogenic action. This study included 20 postmenopausal women that ingested 30 g soy milk daily for 10 weeks. Plasma concentrations of isoflavones and SHBG were measured. Total isoflavones significantly increased from 0.014 +/- 0.01 micromol/L (baseline) to 0.53 +/- 0.19 ,micromol/L, and paired responses showed that some subjects clearly increased their SHBG levels. The percent change in SHBG showed a positive correlation with phytoestrogen concentration; all women who had circulating phytoestrogen levels above 0.6 micromol/L increased by at least 30% their SHBG values. Results suggest that phytoestrogens may significantly increase SHBG in subjects whose SHBG concentrations are in the low end of the concentration range.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Beverages*
  • Body Mass Index
  • Estradiol / blood
  • Estrogens, Non-Steroidal / blood
  • Estrone / blood
  • Female
  • Follicle Stimulating Hormone / blood
  • Humans
  • Isoflavones / administration & dosage
  • Isoflavones / blood
  • Isoflavones / pharmacology*
  • Middle Aged
  • Phytoestrogens
  • Plant Preparations
  • Postmenopause / blood*
  • Regression Analysis
  • Sex Hormone-Binding Globulin / analysis
  • Sex Hormone-Binding Globulin / metabolism*
  • Soybeans*


  • Estrogens, Non-Steroidal
  • Isoflavones
  • Phytoestrogens
  • Plant Preparations
  • Sex Hormone-Binding Globulin
  • Estrone
  • Estradiol
  • Follicle Stimulating Hormone